在ansible中未定义变量时如何运行任务? [英] How to run a task when variable is undefined in ansible?

问题描述

我正在寻找一种在 ansible 变量未注册/未定义时执行任务的方法，例如

I am looking for a way to perform a task when ansible variable is not registers /undefined e.g

-- name: some task
   command:  sed -n '5p' "{{app.dirs.includes}}/BUILD.info" | awk '{print  $2}'
   when: (! deployed_revision) AND ( !deployed_revision.stdout )
   register: deployed_revision

推荐答案

来自 ansible 文档:如果未设置必需的变量，您可以使用 Jinja2 的定义测试跳过或失败.例如:

From the ansible docs: If a required variable has not been set, you can skip or fail using Jinja2’s defined test. For example:

tasks:

- shell: echo "I've got '{{ foo }}' and am not afraid to use it!"
  when: foo is defined

- fail: msg="Bailing out. this play requires 'bar'"
  when: bar is not defined

所以在你的情况下，when: deploy_revision is not defined 应该可以工作

So in your case, when: deployed_revision is not defined should work

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